No regrets whatsoever. I loved my iPhone 4 but the 5 is so much better in every way. Better battery, lighter, faster, better screen.
I never jailbroke the 4 so this isn't an issue. My 5 is flawless, no scratches, no dings and works perfectly; so all in all a happy customer.
I have a screen protector and a clear case on it as the nature of my job means I can't baby the phone. When I sold the 4 it was perfect in every way and the 5 will have the same treatment so when I sell it in the future I can get top price for it.